Timeline

1973:Rowland and Molina first discover that chlorofluorocarbons (CFCs) can destroy stratospheric
ozone.

1974:First government hearings are held on the CFC-ozone theory.

1975:Natural Resources Defense Council sues Consumer Product Safety Commission for a ban on
CFCs used in aerosol spray cans. Lawsuit is rejected due to insufficient evidence that CFCs harm the
ozone layer.

1992: Record levels of ClO, 1.5 parts per billion, are measured over Bangor, Maine.Ozone
depletion rates of up to 20% are found in the Northern Hemisphere.Maximum losses of 40 to 45%
discovered over Russia.

Parties to the Montreal Protocol meet in Geneva and agree to a 75%reduction in CFCs by 1994 and
overall phaseout by January of 1996.

Production grace period, to supply CFCs for essential purposes and the needs of developing countries,
is extended to 2006.